1. Field of the Invention
The present invention relates to a liquid developer for electrophotography, and the present invention can also be applied to printing ink, paint and the like.
2. Description of the Prior Art
A wet type developer for electrophotography uses an aliphatic hydrocarbon having a high boiling point as a dispersing medium. According to the wet type developing system, a developed toner image is fixed when the aliphatic hydrocarbon in the toner diffuses in a copy paper and evaporates in air.
The conventional liquid developer for electrophophotography has disadvantages that its fixativity is not good and consequently that an image of the conventional liquid developer on a copy paper sometimes disappears when rubbed by a finger immediately after a copy is made by the conventional wet type developing copier. This is probably because the diffusion speed of an aliphatic hydrocarbon is low and accordingly the aliphatic hydrocarbon in a toner layer on the copy paper remains for a while.
Carbon and other pigments usually have a porous surface and are liable to adsorb an aliphatic hydrocarbon in a developer on their surfaces. The conventional resin used in the preparation of a coloring agent, including carbon and/or pigments, is easily swellable with the aliphatic hydrocarbon used in the conventional liquid developer, and therefore it is not effective for preventing the aliphatic hydrocarbon from being contained in the coloring agent. Thus, the diffusion speed of the aliphatic hydrocarbon of the conventional developer is low.
Under these circumstances, it is desired to prepare a new developer using a resin effective for preventing an aliphatic hydrocarbon from being contained in a coloring agent, which fixativity is improved by making the diffusion speed of the aliphatic hydrocarbon higher.